1. Field of the Invention
The present invention relates to a semiconductor apparatus, particularly to the structure of a thin film transistor (abbreviated as xe2x80x9cTFTxe2x80x9d) by which liquid crystal of an active matrix display unit is driven.
2. Description of the Related Art
A liquid crystal display unit of an active matrix driving type using a TFT as a driving element included in a thin semiconductor apparatus enabling low power to be consumed has high performance like advanced contrast and high speed response. Consequently, a liquid crystal display unit is mainly used as a display unit of a personal computer or the like or mounted on a portable television receiving apparatus or the like. The scale of the market for such a liquid crystal display unit has largely expanded in recent years.
FIG. 6 is a plan view showing a conventional liquid crystal panel 1. FIG. 7 is a cross sectional view viewed from a cross sectional line VIIxe2x80x94VII in FIG. 6. The liquid crystal panel 1 comprises a light transmitting substrate 3, semiconductor pieces 2 each having a source region 4, a channel region 5 and a drain region 6, a gate insulating film 7, scanning lines 8, auxiliary capacitor electrodes 9, a first interlayer insulating film 10, signal lines 11, drain electrodes 12, a second interlayer insulating film 13 and pixel electrodes 14. The channel region 5 of the semiconductor piece 2 is a semiconductor. The source region 4 and the drain region 6 are electrically conductive because of impurity injected into the semiconductor.
Furthermore, signal line contact holes 15, drain electrode contact holes 16 and pixel electrode contact holes 17 are formed in the liquid crystal panel 1. The signal line 11 is electrically connected to the source region 4 of the semiconductor piece 2 via the signal line contact hole 15. Furthermore, the drain electrode 12 is electrically connected to the drain region 6 of the semiconductor piece 2 via the drain electrode contact hole 16. In addition, the pixel electrode 14 is electrically connected to the drain electrode 12 of the semiconductor piece 2 via the pixel electrode contact hole 17. As to such a liquid crystal panel 1, the TFT has a structure at least including the semiconductor piece 2 having the source region 4 electrically connected to the signal line 11, the channel region 5 electrically connected to the scanning line 8 and the drain region 6 electrically connected to the pixel electrode 14.
In such a conventional liquid crystal panel 1, one signal line contact hole 15 is usually formed for one semiconductor piece 2. As an example of a defective of the signal line contact hole 15, there are a resist defective and a so-called opening defective of a contact hole which means that no signal line contact hole 15 is formed in spite of performing etching because of dust contamination during manufacturing. When there is occurrence of opening defective on the opening of the signal line contact hole 15 for some reason, the signal line 11 can not be electrically connected to the source region 4 of the TFT 2, and thereby signal voltage can not be applied to the TFT facing the signal line contact hole with occurrence of the defective. Thereby, the TFT comprising the semiconductor piece 2 can not apply driving voltage from the drain region 4 to the pixel electrode 14 by applying the signal voltage from the signal line 11 to the source region 4 and from the scanning line 8 to the channel region 5.
Such a pixel without capability of liquid crystal driving is called a point defect and is displayed in black or white on a liquid crystal panel. This point defect can be easily recognized by the eyes of human and therefore no point defect should exist on a liquid crystal panel. With existence of any point defect on the liquid crystal panel, the whole of the liquid crystal panel becomes defective and the panel can not be used for a liquid crystal display unit. Accordingly, eliminating point defect is an important countermeasure item leading to quality improvement of a liquid crystal panel and furthermore reduction of production cost of the panel.
Consequently, an object of the invention is to provide a semiconductor apparatus which simplifies a structure and reduces a possibility of occurrence of manufacture defect.
The invention provides a semiconductor apparatus comprising:
a plurality of signal lines extending in one direction and arranged substantially in parallel each other;
a plurality of scanning lines extending in the other direction intersecting in one direction and arranged substantially in parallel each other;
a plurality of driving electrodes arranged in the form of a matrix; and
switching elements having a source region electrically connected to the signal line, a channel region electrically connected to the scanning line and a drain region electrically connected to a driving electrode, for applying driving voltage from the drain region to the driving electrode by applying signal voltage from the signal line to the source region and from the scanning line to the channel region, the switching elements being formed so that every two of the plurality of switching elements which are adjoined in one direction are integrated in one semiconductor piece.
According to the invention, two switching elements which are adjoined in one direction are integrated in one semiconductor piece, therefore, a number of semiconductor pieces required for forming a predetermined number of switching elements can be reduced half and the structure of the semiconductor apparatus can be simplified, in comparison with such a conventional semiconductor apparatus that one switching element can be formed for one semiconductor piece. When the semiconductor apparatus is manufactured, it is necessary to manufacture the semiconductor apparatus so that all the switching elements can perform such a predetermined operation that driving voltage is applied from the drain region to the driving electrode by applying signal voltage from the signal line to the source region and from the scanning line to the channel region. For this purpose, all the semiconductor pieces should be formed at least in a predetermined shape when the semiconductor apparatus is manufactured. The less a number of semiconductor pieces to be formed becomes, the easier all the semiconductor pieces can be formed into the predetermined shape. In the semiconductor apparatus according to the invention, therefore, a degree of forming all the semiconductor pieces into the predetermined shape becomes twice in comparison with the conventional semiconductor apparatus. In other words, a degree that all the switching elements can perform the predetermined operation becomes twice. Consequently, the semiconductor apparatus according to the invention can halve a possibility of occurrence of manufacturing failure in comparison with the conventional semiconductor apparatus.
According to the invention, in comparison with such a conventional semiconductor apparatus that one switching element is formed for one semiconductor piece, the structure of the semiconductor apparatus can be simplified and the possibility of occurrence of manufacturing failure can be reduced half.
In addition, in the invention it is preferable that the two switching elements share the source region.
According to the invention, the two switching elements integrated in one semiconductor piece share the source region electrically connected to the signal line. A number of source regions electrically connected to the signal line, therefore, is reduced half and the structure of the semiconductor apparatus can be simplified, in comparison with such a conventional semiconductor apparatus that one switching element can be formed for one semiconductor piece. When the semiconductor apparatus is manufactured, it is necessary to manufacture the semiconductor apparatus so that all the switching elements can perform such a predetermined operation that driving voltage is applied from the drain region to the driving electrode by applying signal voltage from the signal line to the source region and from the scanning line to the channel region. For this purpose, all of the source regions and the signal lines should be at least electrically connected to each other when the semiconductor apparatus is manufactured. The less the number of source regions to be connected to the signal lines becomes, the easier all of the source regions and the signal lines can be electrically connected to each other. In the semiconductor apparatus according to the invention, therefore, a degree that all of the source regions and the signal lines are electrically connected to each other becomes twice in comparison with the conventional semiconductor apparatus. In other words, a degree that all the switching elements can perform the predetermined operation becomes twice. Consequently, the semiconductor apparatus according to the invention can halve a possibility of occurrence of manufacturing failure in comparison with the conventional semiconductor apparatus.
In addition, according to the invention, in comparison with such a conventional semiconductor apparatus that one switching element can be formed for one semiconductor piece, the structure of the semiconductor apparatus according to the invention can be simplified and the possibility of occurrence of manufacturing failure can be certainly reduced half.
In addition, in the invention it is preferable that the two switching elements have a symmetrical shape in relation to the source region.
According to the invention, the two switching elements integrated in one semiconductor piece have the symmetrical shape in relation to the source region. Therefore, the two switching elements can be provided with the same characteristics. When the same signal voltage is applied from the signal line and the scanning line to both the switching elements respectively, the same driving voltage is applied from a drain region of each switching element to the driving electrode. Therefore, a driving object connected to the driving electrode can be uniformly driven for the whole of the semiconductor apparatus.
In addition, according to the invention, the driving object connected to the driving electrode can be uniformly driven for the whole of the semiconductor apparatus.
Additionally, in the invention it is preferable that the two scanning lines electrically connected to the two switching elements are symmetrically arranged in relation to the source region, the drain electrodes for electrically connecting each of the driving electrodes to each of the drain regions of the two switching elements are symmetrically arranged in relation to the source region, and auxiliary capacitor lines for forming each auxiliary capacitor between each of the auxiliary capacitor lines and each of the drain electrodes electrically connected to the two switching elements are symmetrically arranged in relation to the source region.
According to the invention, the two scanning lines which are electrically connected to the two switching elements integrated in one semiconductor piece, the drain electrodes for electrically connecting each of the driving electrodes to each of the drain regions of the two switching elements integrated in one semiconductor piece and the auxiliary capacitor lines for forming auxiliary capacitor between each of the auxiliary capacitor lines and each of the drain electrodes electrically connected to the two switching elements integrated in one semiconductor piece are symmetrically arranged in relation to the source region. Therefore, the two switching elements and the two auxiliary capacities can be certainly provided with the same characteristics. Thereby, when the same signal voltage is applied from any signal line and scanning line to both the switching elements, the same driving voltage is applied from the drain region of each switching element to the driving electrode. A driving object connected to the driving electrode, therefore, can be uniformly driven on the whole of the semiconductor apparatus. In addition, when the same signal voltage is applied from the signal line to the source region and from the scanning line to the channel region, a charge is accumulated in the auxiliary capacitor. Therefore, even when signal voltage is not applied to the switching element, the same voltage as the driving voltage can be applied to the driving electrode by the auxiliary capacitor in which the charge is accumulated.
In addition, according to the invention, the driving object connected to the driving electrode can be uniformly driven on the whole of the semiconductor apparatus and even when signal voltage is not applied to the switching element, the same voltage as the driving voltage retained in the auxiliary capacitor can be applied to the driving electrode.
In addition, in the invention it is preferable that at least a part of each of the channel regions of the two switching elements is located on a position opposite to the signal line in a direction perpendicular to one direction and perpendicular to the other direction.
According to the invention, at least a part of each of channel regions of the two switching elements integrated in one semiconductor piece is arranged on a position opposite to the signal line in the direction perpendicular to one direction and perpendicular to the other direction. For example, when the semiconductor apparatus is used for the liquid crystal display unit, a region in which the signal line is located serves as a light shielding region for shielding light traveling in the direction perpendicular to one direction and perpendicular to the other direction. By locating at least each of the part of the channel regions on the position opposite to the signal line in relation to the light traveling direction, more increase of the light shielding region caused by the channel region is prevented and a predetermined light transmission region can be secured. In addition, since a region in which the channel region is located is included in the region in which the signal line is located, a predetermined auxiliary capacity can be secured without decrease of a region in which the auxiliary capacitor line is located, i.e., an area of the auxiliary capacitor line.
In addition, according to the invention, more increase of the light shielding region caused by the channel region is prevented, and not only the predetermined light transmission region, but also the predetermined auxiliary capacity can be secured in the semiconductor apparatus.
In addition, the invention provides a method of manufacturing a semiconductor apparatus comprising the steps of:
forming a semiconductor layer on a substrate and two drain regions on the semiconductor layer;
forming a gate insulating film on the substrate so as to cover the semiconductor layer;
forming scanning lines and auxiliary capacitor lines on the gate insulating film;
forming one source region between the two drain regions of the semiconductor layer and forming channel regions between the drain regions and the source region of the semiconductor layer;
forming a first interlayer insulating film on the gate insulating film so as to cover the scanning lines and the auxiliary capacitor lines and forming a signal line contact hole facing the source region and drain region contact holes each facing the drain region, the signal line contact hole and the drain region contact holes piercing both the gate insulating film and the first interlayer insulating film in a direction in which each insulating layer is stacked;
forming, on the first interlayer insulating film, a signal line which is connected to the source region via the signal line contact hole and forming drain electrodes each of which is connected to each of the drain regions of the semiconductor layer via each of the drain region contact holes;
forming a second interlayer insulating film on the first interlayer insulating film so as to cover the signal line and the drain electrodes and forming driving electrode contact holes each facing each of the drain electrodes, the each of the driving electrode contact holes piercing the second interlayer insulating film in the direction in which each insulating layer is stacked; and
forming, on the second interlayer insulating film, driving electrodes each of which is connected to each of the drain electrodes via each of the driving electrode contact holes.
According to the invention, the semiconductor by which the above-mentioned operation can be achieved can be manufactured.